When Intelligence Fails: An Empirical Study on Why LLMs Struggle with Password Cracking

Fuente: arXiv
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Main Authors: Rehman, Mohammad Abdul, Shah, Syed Imad Ali, Anwar, Abbas, Islam, Noor, Khan, Hamid
Format: Preprint
Published: 2025
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author Rehman, Mohammad Abdul
Shah, Syed Imad Ali
Anwar, Abbas
Islam, Noor
Khan, Hamid
author_facet Rehman, Mohammad Abdul
Shah, Syed Imad Ali
Anwar, Abbas
Islam, Noor
Khan, Hamid
contents The remarkable capabilities of Large Language Models (LLMs) in natural language understanding and generation have sparked interest in their potential for cybersecurity applications, including password guessing. In this study, we conduct an empirical investigation into the efficacy of pre-trained LLMs for password cracking using synthetic user profiles. Specifically, we evaluate the performance of state-of-the-art open-source LLMs such as TinyLLaMA, Falcon-RW-1B, and Flan-T5 by prompting them to generate plausible passwords based on structured user attributes (e.g., name, birthdate, hobbies). Our results, measured using Hit@1, Hit@5, and Hit@10 metrics under both plaintext and SHA-256 hash comparisons, reveal consistently poor performance, with all models achieving less than 1.5% accuracy at Hit@10. In contrast, traditional rule-based and combinator-based cracking methods demonstrate significantly higher success rates. Through detailed analysis and visualization, we identify key limitations in the generative reasoning of LLMs when applied to the domain-specific task of password guessing. Our findings suggest that, despite their linguistic prowess, current LLMs lack the domain adaptation and memorization capabilities required for effective password inference, especially in the absence of supervised fine-tuning on leaked password datasets. This study provides critical insights into the limitations of LLMs in adversarial contexts and lays the groundwork for future efforts in secure, privacy-preserving, and robust password modeling.
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id arxiv_https___arxiv_org_abs_2510_17884
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publishDate 2025
record_format arxiv
spellingShingle When Intelligence Fails: An Empirical Study on Why LLMs Struggle with Password Cracking
Rehman, Mohammad Abdul
Shah, Syed Imad Ali
Anwar, Abbas
Islam, Noor
Khan, Hamid
Cryptography and Security
Artificial Intelligence
Machine Learning
The remarkable capabilities of Large Language Models (LLMs) in natural language understanding and generation have sparked interest in their potential for cybersecurity applications, including password guessing. In this study, we conduct an empirical investigation into the efficacy of pre-trained LLMs for password cracking using synthetic user profiles. Specifically, we evaluate the performance of state-of-the-art open-source LLMs such as TinyLLaMA, Falcon-RW-1B, and Flan-T5 by prompting them to generate plausible passwords based on structured user attributes (e.g., name, birthdate, hobbies). Our results, measured using Hit@1, Hit@5, and Hit@10 metrics under both plaintext and SHA-256 hash comparisons, reveal consistently poor performance, with all models achieving less than 1.5% accuracy at Hit@10. In contrast, traditional rule-based and combinator-based cracking methods demonstrate significantly higher success rates. Through detailed analysis and visualization, we identify key limitations in the generative reasoning of LLMs when applied to the domain-specific task of password guessing. Our findings suggest that, despite their linguistic prowess, current LLMs lack the domain adaptation and memorization capabilities required for effective password inference, especially in the absence of supervised fine-tuning on leaked password datasets. This study provides critical insights into the limitations of LLMs in adversarial contexts and lays the groundwork for future efforts in secure, privacy-preserving, and robust password modeling.
title When Intelligence Fails: An Empirical Study on Why LLMs Struggle with Password Cracking
topic Cryptography and Security
Artificial Intelligence
Machine Learning
url https://arxiv.org/abs/2510.17884